JWST has revealed a stunning population of bright galaxies at surprisingly early epochs, z>10, where few such sources were expected. Here we present the most distant example of this class yet – MoM-z14, a luminous (M_UV=-20.2) source in the COSMOS field at z_spec=14.44^+0.02_-0.02 that expands the observational frontier to a mere 280 million years after the Big Bang. The redshift is confirmed with NIRSpec/PRISM spectroscopy through a sharp Lyman-α break and ∼3σ detections of five rest-UV emission lines. The number density of bright z_spec∼14-15 sources implied by our "Mirage or Miracle" survey spanning ∼350 arcmin^2 is >100× larger (182^+329_-105×) than pre-JWST consensus models. The high EWs of UV lines (∼15-35 Å) signal a rising star-formation history, with a ∼10× increase in the last 5 Myr (SFR_5Myr/SFR_50Myr=9.9^+3.0_-5.8). The source is extremely compact (circularized r_e = 74^+15_-12 pc), and yet elongated (b/a=0.25^+0.11_-0.06), suggesting an AGN is not the dominant source of UV light. The steep UV slope (β=-2.5^+0.2_-0.2) implies negligible dust attenuation and a young stellar population. The absence of a strong damping wing provides tentative evidence that the immediate surroundings of MoM-z14 may be partially ionized at a redshift where virtually every reionization model predicts a ∼100% neutral fraction. The nitrogen emission and highly super-solar [N/C]>1 hint at an abundance pattern similar to local globular clusters that may have once hosted luminous supermassive stars. Since this abundance pattern is also common among the most ancient stars born in the Milky Way, we may be directly witnessing the formation of such stars in dense clusters, connecting galaxy evolution across the entire sweep of cosmic time.

The unexpectedly high abundance of galaxies at z > 11 revealed by JWST has sparked a debate on the nature of early galaxies and the physical mechanisms regulating their formation. The Atacama Large Millimeter/submillimeter Array (ALMA) has begun to provide vital insights on their gas and dust content, but so far only for extreme 'blue monsters'. Here we present new, deep ALMA observations of JADES-GS-z11-0, a more typical (sub-L^*) z > 11 galaxy that bridges the discovery space of JWST and the Hubble Space Telescope. These data confirm the presence of the [O III] 88 μm line at 4.5σ significance, precisely at the redshift of several faint emission lines previously seen with JWST/NIRSpec, while the underlying dust continuum remains undetected (F_ν< 9.0 μJy), implying an obscured star formation rate (SFR) of SFR_IR≲ 6 M_⊙ yr^-1 and dust mass of M_dust≲ 1.0 × 10^6 M_⊙ (all 3σ). The accurate ALMA redshift of z_[O III] = 11.1221 ± 0.0006 (≳ 5× refined over NIRSpec) helps confirm that redshifts measured purely from the Lyman-α break, even spectroscopically, should properly take into account the effects of potential damped Lyman-α absorption (DLA) systems to avoid systematic overestimates of up to Δz ≈ 0.5. The [O III] 88 μm luminosity of L_[O III] = (1.0 ± 0.3) × 10^8 L_⊙, meanwhile, agrees well with the scaling relation for local metal-poor dwarfs given the SFR measured by NIRCam, NIRSpec, and MIRI. The spatially resolved MIRI and ALMA emission also underscores that JADES-GS-z11-0 is likely to consist of two low-mass components that are undergoing strong bursts of star formation yet are already pre-enriched in oxygen ( 30

Mergers of neutron stars are believed to be one of the primary sites for the synthesis of the universe's heavy elements via the rapid neutron capture process. AT2017gfo, the kilonova following GW170817 provided the first direct spectroscopic evidence of the r-process happening in the universe. A prominent line feature near 1 μm in its spectrum was attributed to strontium – a claim that has been independently recovered by several teams. However, in recent years it has been debated whether the feature arises instead from helium. Here, we present non–local thermodynamic equilibrium (NLTE) radiative transfer modelling of the observed kilonova spectra, including detailed radiation-matter interaction physics for both strontium and helium. We make use of freshly calculated strontium atomic data for e^- impact collisions, photoionization, and recombination processes. Our strontium model self-consistently reproduces the temporal evolution of the 1 μm feature at early times, with its absence at 0.92days to its clear emergence at 1.17days. This transition mimics LTE, because at early epochs (t≲ 1.5days) the radiation field dominates the ionization state of the ejecta over thermal and non-thermal electron collisions. We further test if helium can form the feature under the same plasma conditions. The helium mass required at 1.17days is comparable to the total ejecta mass, while a few percent by mass of helium suffices at 4.4 days. On the other hand, the strength of the strontium lines decrease with time, and may require a radially stratified abundance to consistently produce the feature. We conclude that strontium is required to explain the onset of the feature at early times, but helium can contribute to, or even dominate the feature at later epochs.

Little red dots (LRDs) are candidate high-redshift supermassive black holes accreting in dense gas. They remain undetected in X-rays. In previous work, we provided the first quantitative models that reproduce the optical and near-infrared spectra of LRDs with the radiative transfer code, thereby constraining the properties of the surrounding gas. Here, we use these constraints to predict the X-ray attenuation produced by dense gas cocoons, and explore its dependence on Balmer-break strength, metallicity, intrinsic X-ray spectral energy distribution, and observed bandpass as a function of redshift. The X-ray constraints are very tight, requiring extinction by a Compton-thick gas column (N_ H∼10^25 cm^-2) with moderate metallicity 0.05-0.1 Z_⊙ and intrinsically weak X-ray emission (bolometric to X-ray luminosity ratio, k_ bol,X≳ 30), as observed in narrow-line active galactic nuclei with high accretion rates, to make LRDs sufficiently faint to evade detection. Intrinsically bright X-ray emitters as seen in typical broad-line active galactic nuclei would be detected even behind the typical Compton-thick gas columns with modest metallicity that were inferred from the optical spectra. Very low metallicity objects might be detected in X-rays even with low intrinsic X-ray luminosities, suggesting that LRDs are not (currently) chemically pristine.

The mass assembly and chemical enrichment of the first galaxies provide key insights into their star formation histories and the earliest stellar populations at cosmic dawn. Here we compile and utilise new, high-quality spectroscopic JWST/NIRSpec Prism observations from the JWST archive. In particular, we extend the wavelength coverage beyond the standard pipeline cut-off (5.3 μm) up to 5.5 μm, which enables for the first time a detailed examination of the rest-frame optical emission-line properties for galaxies at z ≈ 10. Crucially, the improved calibration allows us to detect Hβ and the [O III] λλ4959, 5007 doublet and resolve the auroral [O III] λ4363 line for the 11 galaxies in our sample (z = 9.3 − 10.0) to obtain direct Te-based metallicity measurements. We find that the interstellar medium (ISM) of all galaxies shows high ionisation fields and electron temperatures, with derived metallicities in the range 12 + log(O/H) = 7.1 − 8.3 (3–50% solar), consistent with previous strong-line diagnostics based on JWST data at high redshifts. We derive an empirical relation for MUV and 12 + log(O/H) at z ≈ 10, useful for future higher-redshift studies, and show that the sample galaxies are ‘typical’ star-forming galaxies though with relatively high specific star formation rates (median sSFR = SFRHβ/M★ = 38 Gyr−1) and with evidence of bursty star formation on 10 Myr versus 100 Myr timescales (log10(SFR10/SFR100)≈0.7). Combining the rest-frame optical line analysis and detailed UV to optical spectro-photometric modelling, we determine the mass-metallicity relation (MZR) and the fundamental metallicity relation (FMR) of the sample, pushing the previous redshift frontier of these measurements to z = 10. These results, together with literature measurements, point to a gradually decreasing MZR at higher redshifts, with a break in the FMR at z ≈ 3, decreasing to metallicities ≈3× lower at z = 10 than observed in galaxies during the majority of cosmic time at z = 0 − 3, likely caused by massive pristine gas inflows diluting the observed metal abundances during early galaxy assembly at cosmic dawn.

”Little Red Dots” (LRDs) are broad-line sources at high redshift, initially identified by their compact morphologies, red colours and prominent Balmer breaks. The origin of their optical-to-near-infrared continua is debated, with proposed explanations ranging from direct recombination emission to thermalised blackbodies from stellar-like atmospheres. Here we report evidence for Paschen jumps in a subset of LRDs, consistent with free-bound recombination to hydrogen n=3. The Paschen and Brackett continuum shapes across the sample are consistent with minimally reddened emission from low-temperature gas with T_e≲10 000 K, while the presence of Paschen jump signatures limits scenarios in which the emission is thermalised. Further, the extreme Hα equivalent widths and the tight observed correlation between Hα and the continuum follow naturally if both originate in recombination emission. This provides an observational upper limit on the contribution of any direct AGN accretion component and any stellar-atmosphere-like component, as well as on the fraction of line emission that can be thermalised as it traverses the cocoon. Ultimately, nebular radiative-transfer models provide a self-consistent explanation of the continuum, line strengths and line profiles without requiring multiple separately fitted components.

The discovery of galaxies with extremely strong nebular continuum emission at high redshifts provide novel, unique insights into the conditions under which the first super-massive stars formed. Here we identify a galaxy at redshift z=5.124 observed by the JWST CAPERS survey that exhibits a prominent turnover in the rest-frame UV continuum and a pronounced Balmer `jump'. We model the entire JWST/NIRSpec Prism spectrum from rest-frame UV to optical wavelength, finding that a dominant (>95%) nebular continuum emission can accurately reproduce the spectral shape across all wavelengths. We tested an alternative model with strong damped Lyα absorption (DLA), but found that it is not able to match the shape of the turnover without invoking a large freedom in the redshift of the absorber. The nebular continuum emission model reveals a hot (T = (5.3± 0.2)× 10^4 K) and dense (n_e = (5.4± 0.8)× 10^3 cm^-3) nebular region powering the origin of the spectral shape. We also note the presence of a `blue' candidate companion source potentially at the same redshift, offset by 3 kpc to the main galaxy. Intriguingly, the spectrum of this source show several hints of hydrogen and helium lines, but no metal lines are detected. We theorize that this companion galaxy might be comprised mainly of Population III (PopIII) stellar remnants and potentially powers the nebular continuum emission seen in the main galaxy. These results have important implications for the presence of a potential dominant population of super-massive and PopIII stars and their consequent excess UV brightness for a significant fraction of galaxies at cosmic dawn.

The time until black-hole formation in a binary neutron-star (NS) merger contains invaluable information about the nuclear equation of state (EOS) but has thus far been difficult to measure. We propose a new way to constrain the merger remnant's NS lifetime, which is based on the tendency of the NS-remnant neutrino-driven winds to enrich the ejected material with helium. Based on the He I lambda 1083.3 nm line, we show that the feature around 800-1200 nm in AT2017gfo at 4.4 days seems inconsistent with a helium mass fraction of XHe greater than or similar to 0.05 in the polar ejecta. Our recent neutrino-hydrodynamic simulations of merger remnants are only compatible with this limit if the NS remnant collapses within 20-30 ms. Such a short lifetime implies that the total binary mass of GW170817, Mtot, lay close to the threshold binary mass for direct gravitational collapse, Mthres, for which we estimate Mthres less than or similar to 2.93Mo. This upper bound on Mthres yields upper limits on the radii and maximum mass of cold, nonrotating NSs, which rule out simultaneously large values for both quantities. In combination with causality arguments, this result implies a maximum NS mass of Mmax less than or similar to 2.3Mo. We include an updated constraint yielding lower limits on NS radii from a previous argument that the remnant did not promptly collapse, which is independent of the consideration of the helium content. The combination of all limits constrains the radii of 1.6Mo NSs to about 12 + 1 km for Mmax = 2.0Mo and 11.5 + 1 km for Mmax = 2.15Mo. This similar to 2 km allowable range tightens significantly for Mmax above approximate to 2.15Mo. This rules out a significant number of current EOS models. The short NS lifetime also implies that a black-hole torus, not a highly magnetized NS, was the central engine powering the relativistic jet of GRB170817A. Our work motivates future developments to further corroborate and improve uncertainties in our chain of arguments regarding non-local-thermodynamic-equilibrium spectral modeling, helium production in merger outflows, and the dependence of the remnant lifetime on the binary mass, with the potential to tighten our constraints from existing data and in particular from future events. This novel method may provide a powerful tool to get a handle on the poorly constrained remnant lifetime, the still debated central engine of short gamma-ray bursts, and the high-density EOS.

Recent observations have revealed a remarkably rapid buildup of cosmic dust in the interstellar medium (ISM) of high redshift galaxies, with complex dust compositions and large abundances already appearing at redshifts z>6. Here we present a comprehensive, joint analysis of observations taken with the James Webb Space Telescope (JWST) and the Atacama Large Millimetre/sub-millimetre Array (ALMA) of the highly magnified, dusty `normal' galaxy, A1689-zD1 at z=7.13. We perform detailed spectro-photometric modeling of the rest-frame UV to far-infrared spectral energy distribution (SED) based on archival photometry of the source and report new rest-frame optical strong-line measurements and metallicity estimates from recent JWST/NIRSpec IFU data. We find that despite its substantial dust mass, M_ dust∼ 1.5× 10^7 M_⊙, A1689-zD1 has remarkably low dust-to-gas and dust-to-metal mass ratios, DTG = (5.1^+3.0_-1.9)× 10^-4 and DTM = (6.1^+3.6_-2.3)× 10^-2, respectively, due to its high metallicity 12+log( O/H) = 8.36± 0.10 and substantial gas mass, M_ gas = (2.8^+0.2_-1.7)× 10^10 M_⊙. The DTG and DTM mass ratios are an order of magnitude lower than expected for galaxies in the local universe with similar chemical enrichment. These low relative measurements are also corroborated by the deficit observed in the A_V/N_ HI ratio of A1689-zD1 in the line-of-sight. We find that this deviation in the DTG and DTM mass ratios appears to be ubiquitous in other metal-rich galaxies at similar redshifts, z≳ 6. This suggests that the processes that form and destroy dust at later times, or the dust emissivity itself, are drastically different for galaxies in the early Universe.

Context. X-ray scattering is a powerful probe of the grain-size distribution of interstellar dust. Bright transient sources are excellent tools for this because they fade rapidly and only leave the expanding scattered X-ray halo. Aims. We analysed the dust-scattered X-ray halo data of the unprecedentedly bright gamma-ray burst GRB 221009A to measure the grain-size distribution of dust in the Galaxy as well as the complex refractive index m, and use these results to infer the likely dust composition. Methods. GRB 221009A produced 20 distinct rings, as observed with follow-up observations of the GRB afterglow and scattering halo with the EPIC camera on XMM-Newton. We used anomalous diffraction theory to model the ring brightness as a function of angle. Results. We constrained the complex refractive index m = n + ik at several x-ray energies and found k(1 keV) = (2.7 +/- 0.7) x 10(-4) and 1 - n(1 keV) = 0.0009 +/- 0.0002. This is highly inconsistent with the commonly employed assumptions of the Rayleigh-Gans approximation. These results lie in the expected range for interstellar dust compositions that are dominated by carbon, magnesium silicates, and iron. The absorption results suggest a substantial mass fraction of iron at 35 +/- 7%. The Mathis et al. (1977, ApJ, 217, 425) distribution fit returns a maximum grain radius a(max) = 0.24 +/- 0.01 mu m; all fits strongly rule out models with similar to 0.4 mu m grains for this sightline. The soft X-ray spectrum of the prompt GRB can also be inferred from the fitting, and the best fit provides a spectral slope that is consistent with the slope of the low-energy side of the best-fit Band model of the directly measured prompt emission. Forcing a different grain size or composition than the best fit results in an inferred prompt spectrum that is different from the observed prompt emission. Conclusions. We directly measured the grain-size distribution and refractive index of the interstellar dust. The radius of only a very few grains is larger than about similar to 0.3 mu m. The refractive index is consistent with standard average dust compositions, which shows that X-ray scattering is an effective tool for measuring the optical properties of interstellar dust.

Gamma-ray bursts (GRBs) are singular outbursts of high-energy radiation with durations typically lasting from milliseconds to minutes and, in extreme cases, a few hours. They are attributed to the catastrophic outcomes of stellar-scale events and, as such, are not expected to recur. Here, we present observations of an exceptional GRB 250702BDE which triggered the Fermi gamma-ray burst monitor on three occasions over several hours, and which was detected in soft X-rays by the Einstein Probe a day before the γ-ray triggers (EP250702a). We present the discovery of an extremely red infrared counterpart of the event with the VLT, as well as radio observations from MeerKAT. Hubble Space Telescope observations pinpoint the source to a non-nuclear location in a host galaxy with complex morphology, implying GRB 250702BDE is an extragalactic event. The multi-wavelength counterpart is well described with standard afterglow models at a relatively low redshift z ∼ 0.2, but the prompt emission does not readily fit within the expectations for either collapsar or merger-driven GRBs. Indeed, a striking feature of the multiple prompt outbursts is that the third occurs at an integer multiple of the interval between the first two. Although not conclusive, this could be indicative of periodicity in the progenitor system. We discuss several possible scenarios to explain the exceptional properties of the burst, which suggest that either a very unusual collapsar or the tidal disruption of a white dwarf by an intermediate-mass black hole are plausible explanations for this unprecedented GRB.

The mass assembly and chemical enrichment of the first galaxies provide key insights into their star-formation histories and the earliest stellar populations at cosmic dawn. Here we compile and utilize new, high-quality spectroscopic JWST/NIRSpec Prism observations from the JWST archive. We extend the wavelength coverage beyond the standard pipeline cutoff up to 5.5μm, enabling a detailed examination of the rest-frame optical emission-line properties for galaxies at z≈ 10. The improved calibration allows us to detect Hβ and the [OIII]λλ4959,5007 doublet and resolve the auroral [OIII]λ4363 line for the 11 galaxies in our sample (z=9.3-10.0) to obtain direct T_e-based metallicity measurements. We find that all galaxies show high ionisation fields and electron temperatures, with derived metallicities in the range 12+log (O/H) = 7.1 - 8.3, consistent with previous strong-line diagnostics at high-z. We derive an empirical relation for M_ UV and 12+log(O/H) at z≈ 10, useful for future higher-z studies, and show that the sample galaxies are `typical' star-forming galaxies though with relatively high specific star-formation rates and with evidence for bursty star formation. Combining the rest-frame optical line analysis and detailed UV to optical SED modelling, we determine the mass-metallicity relation and the fundamental-metallicity relation of the sample, pushing the redshift frontier of these measurements to z=10. These results, together with literature measurements, point to a gradually decreasing MZR at higher redshifts, with a break in the FMR at z≈ 3, decreasing to metallicities ≈ 3× lower at z=10 than observed during the majority of cosmic time at z=0-3, likely caused by massive pristine gas inflows diluting the observed metal abundances during early galaxy assembly at cosmic dawn.

Context. One of the surprising early findings with JWST has been the discovery of a strong “roll-over” or a softening of the absorption edge of Lyα in a large number of galaxies at z ≳ 6, in addition to systematic offsets from photometric redshift estimates and fundamental galaxy scaling relations. This has been interpreted as strong cumulative damped Lyα absorption (DLA) wings from high column densities of neutral atomic hydrogen (H I), signifying major gas accretion events in the formation of these galaxies. Aims. To explore this new phenomenon systematically, we assembled the JWST/NIRSpec PRImordial gas Mass AssembLy (PRIMAL) legacy survey of 584 galaxies at z = 5.0 − 13.4, designed to study the physical properties and gas in and around galaxies during the reionization epoch. Methods. We characterized this benchmark sample in full and spectroscopically derived the galaxy redshifts, metallicities, star formation rates, and ultraviolet (UV) slopes. We defined a new diagnostic, the Lyα damping parameter DLyα, to measure and quantify the net effect of Lyα emission strength, the H I fraction in the intergalactic medium, or the local H I column density for each source. The JWST-PRIMAL survey is based on the spectroscopic DAWN JWST Archive (DJA-Spec). We describe DJA-Spec in this paper, detailing the reduction methods, the post-processing steps, and basic analysis tools. All the software, reduced spectra, and spectroscopically derived quantities and catalogs are made publicly available in dedicated repositories. Results. We find that the fraction of galaxies showing strong integrated DLAs with NHI > 1021 cm−2 only increases slightly from ≈60% at z ≈ 6 up to ≈65 − 90% at z > 8. Similarly, the prevalence and prominence of Lyα emission is found to increase with decreasing redshift, in qualitative agreement with previous observational results. Strong Lyα emitters (LAEs) are predominantly found to be associated with low-metallicity and UV faint galaxies. By contrast, strong DLAs are observed in galaxies with a variety of intrinsic physical properties, but predominantly at high redshifts and low metallicities. Conclusions. Our results indicate that strong DLAs likely reflect a particular early assembly phase of reionization-era galaxies, at which point they are largely dominated by pristine H I gas accretion. At z = 8 − 10, this gas gradually cools and forms into stars that ionize their local surroundings, forming large ionized bubbles and producing strong observed Lyα emission at z < 8.

Context: The extreme luminosity of gamma-ray bursts (GRBs) makes them powerful beacons for studies of the distant Universe. The most luminous bursts are typically detected at moderate/high redshift, where the volume for seeing such rare events is maximized and the star-formation activity is greater than at z = 0. For distant events, not all observations are feasible, such as at TeV energies. Aims: Here we present a spectroscopic redshift measurement for the exceptional GRB 221009A, the brightest GRB observed to date with emission extending well into the TeV regime. Methods: We used the X-shooter spectrograph at the ESO Very Large Telescope (VLT) to obtain simultaneous optical to near-IR spectroscopy of the burst afterglow 0.5 days after the explosion. Results: The spectra exhibit both absorption and emission lines from material in a host galaxy at z = 0.151. Thus GRB 221009A was a relatively nearby burst with a luminosity distance of 745 Mpc. Its host galaxy properties (star-formation rate and metallicity) are consistent with those of LGRB hosts at low redshift. This redshift measurement yields information on the energy of the burst. The inferred isotropic energy release, $E_{\rm iso} > 5 \times 10^{54}$ erg, lies at the high end of the distribution, making GRB 221009A one of the nearest and also most energetic GRBs observed to date. We estimate that such a combination (nearby as well as intrinsically bright) occurs between once every few decades to once per millennium.

Early galaxy formation, initiated by the dark matter and gas assembly, evolves through frequent mergers and feedback processes into dynamically hot, chaotic structures. In contrast, dynamically cold, smooth rotating disks have been observed in massive evolved galaxies merely 1.4 billion years after the Big Bang, suggesting rapid morphological and dynamical evolution in the early Universe. Probing this evolution mechanism necessitates studies of young galaxies, yet efforts have been hindered by observational limitations in both sensitivity and spatial resolution. Here we report high-resolution observations of a strongly lensed and quintuply imaged, low-luminosity, young galaxy at $z=6.072$ (dubbed the Cosmic Grapes), 930 million years after the Big Bang. Magnified by gravitational lensing, the galaxy is resolved into at least 15 individual star-forming clumps with effective radii of $r_{\rm e}\simeq$ 10--60 parsec (pc), which dominate $\simeq$ 70\% of the galaxy's total flux. The cool gas emission unveils a smooth, underlying rotating disk characterized by a high rotational-to-random motion ratio and a gravitationally unstable state (Toomre $Q \simeq$ 0.2--0.3), with high surface gas densities comparable to local dusty starbursts with $\simeq10^{3-5}$ $M_{\odot}$/pc$^{2}$. These gas properties suggest that the numerous star-forming clumps are formed through disk instabilities with weak feedback effects. The clumpiness of the Cosmic Grapes significantly exceeds that of galaxies at later epochs and the predictions from current simulations for early galaxies. Our findings shed new light on internal galaxy substructures and their relation to the underlying dynamics and feedback mechanisms at play during their early formation phases, potentially explaining the high abundance of bright galaxies observed in the early Universe and the dark matter core-cusp problem.

The physical processes that led to the formation of billion solar mass black holes within the first 700 million years of cosmic time remain a puzzle. Several theoretical scenarios have been proposed to seed and rapidly grow black holes, but direct observations of these mechanisms remain elusive. Here we present a source 660 million years after the Big Bang that displays singular properties: among the largest Hydrogen Balmer breaks reported at any redshift, broad multi-peaked Hβ emission, and Balmer line absorption in multiple transitions. We model this source as a "black hole star" (BH*) where the Balmer break and absorption features are a result of extremely dense, turbulent gas forming a dust-free "atmosphere" around a supermassive black hole. This source may provide evidence of an early black hole embedded in dense gas – a theoretical configuration proposed to rapidly grow black holes via super-Eddington accretion. Radiation from the BH* appears to dominate almost all observed light, leaving limited room for contribution from its host galaxy. We demonstrate that the recently discovered "Little Red Dots" (LRDs) with perplexing spectral energy distributions can be explained as BH*s embedded in relatively brighter host galaxies. This source provides evidence that black hole masses in the LRDs may be over-estimated by orders of magnitude – the BH* is effectively dust-free contrary to the steep dust corrections applied while modeling LRDs, and the physics that gives rise to the complex line shapes and luminosities may deviate from assumptions underlying standard scaling relations.

At cosmic dawn, the first stars and galaxies are believed to form from and be deeply embedded in clouds of dense, pristine gas. Here we present a study of the James Webb Space Telescope/NIRSpec data of the most distant, spectroscopically confirmed galaxy observed to date, JADES-GS-z14-0 (GS-z14 for short), at z = 14.179, combined with recently reported far-infrared measurements of the [O iii ]-88 μ m and [C ii ]-158 μ m line transitions and underlying dust-continuum emission. Based on the observed prominent damped Ly α (DLA) absorption profile, we determine a substantial neutral atomic hydrogen (H i ) column density, log ( N HI / cm − 2 ) = 22.2 7 − 0.09 + 0.08 , consistent with previous estimates though seemingly at odds with the dynamical and gas mass of the galaxy. Using various independent but complementary approaches, considering the implied neutral gas mass from the DLA measurement, the star formation rate surface density, and the metal abundance, we demonstrate that the total gas mass of GS-z14 is of the order M gas = 10 9.5 –10 9.8 M ⊙ . This implies a substantial gas mass fraction, f gas ≈ 0.7–0.9 and that the bulk of the interstellar medium (ISM) is in the form of H i , with mass ratios M HI / M H 2 ≈ 3 . We show that the derived gas mass is fully consistent with the nondetection of [C ii ]-158 μ m, assuming an appropriate scaling to the neutral gas. The low dust-to-gas ratio, A V / N HI = (1.3 ± 0.6) × 10 −23 mag cm 2 , derived in the line of sight through the DLA further indicates that the absorbing gas is more pristine than the central, star-forming regions probed by the [O iii ]-88 μ m emission. These results highlight the implications for far-infrared line-detection searchers attainable with the Atacama Large Millimeter/submillimeter Array and demonstrate that the bright, relatively massive galaxy GS-z14 at z = 14.179 is deeply embedded in a substantial, pristine H i gas reservoir dominating its baryonic matter content.

Planetary materials show systematic variations in their nucleosynthetic isotope compositions that resonate with orbital distance. The origin of this pattern remains debated, limiting how these isotopic signatures can be used to trace the precursors of terrestrial planets. Here we test the hypothesis that interstellar ices carried supernova-produced nuclides by searching for a supernova nucleosynthetic fingerprint in aqueous alteration minerals from carbonaceous and non-carbonaceous chondrite meteorites. We focus on zirconium, a refractory element that includes the neutron-rich isotope ^96Zr formed in core-collapse supernovae. Leaching experiments reveal extreme ^96Zr enrichments in alteration minerals, showing that they incorporated supernova material hosted in interstellar ices. We show that the Solar System's zirconium isotope variability reflects mixing between these ices and an ice-free rocky component. Finally, the presence of supernova nuclides in a volatile carrier supports models where the Solar System's nucleosynthetic variability was imparted by thermal processing of material in the protoplanetary disk and during planetary accretion.

γ -ray bursts (GRBs) are singular outbursts of high-energy radiation with durations typically lasting from milliseconds to minutes and, in extreme cases, a few hours. They are attributed to the catastrophic outcomes of stellar-scale events and, as such, are not expected to recur. Here, we present observations of the exceptional GRB 250702B (formerly GRB 250702BDE) which triggered the Fermi GRB monitor on three occasions over several hours, and which was detected in soft X-rays by the Einstein Probe several hours before the γ -ray triggers (EP 250702a). We present the discovery of an extremely red infrared counterpart of the event with the Very Large Telescope, as well as radio observations from MeerKAT. Hubble Space Telescope observations pinpoint the source to a nonnuclear location in a host galaxy with complex morphology, implying GRB 250702B is an extragalactic event. The multiwavelength counterpart is well described with standard afterglow models at a relatively low redshift z ∼ 0.3, but the prompt emission does not readily fit within the expectations for either collapsar or merger-driven GRBs. Indeed, a striking feature of the multiple prompt outbursts is that the third occurs at an integer multiple of the interval between the first two. Although not conclusive, this could be indicative of periodicity in the progenitor system. We discuss several possible scenarios to explain the exceptional properties of the burst, which suggest that either a very unusual collapsar or the tidal disruption of a white dwarf by an intermediate-mass black hole are plausible explanations for this unprecedented GRB.

Context. One of the surprising early findings with JWST has been the discovery of a strong "roll-over" or a softening of the absorption edge of Ly alpha in a large number of galaxies at z greater than or similar to 6, in addition to systematic offsets from photometric redshift estimates and fundamental galaxy scaling relations. This has been interpreted as strong cumulative damped Ly alpha absorption (DLA) wings from high column densities of neutral atomic hydrogen (H I), signifying major gas accretion events in the formation of these galaxies. Aims. To explore this new phenomenon systematically, we assembled the JWST/NIRSpec PRImordial gas Mass AssembLy (PRIMAL) legacy survey of 584 galaxies at z = 5.0 - 13.4, designed to study the physical properties and gas in and around galaxies during the reionization epoch. Methods. We characterized this benchmark sample in full and spectroscopically derived the galaxy redshifts, metallicities, star formation rates, and ultraviolet (UV) slopes. We defined a new diagnostic, the Ly alpha damping parameter D-Ly alpha, to measure and quantify the net effect of Ly alpha emission strength, the H I fraction in the intergalactic medium, or the local H I column density for each source. The JWST-PRIMAL survey is based on the spectroscopic DAWN JWST Archive (DJA-Spec). We describe DJA-Spec in this paper, detailing the reduction methods, the post-processing steps, and basic analysis tools. All the software, reduced spectra, and spectroscopically derived quantities and catalogs are made publicly available in dedicated repositories. Results. We find that the fraction of galaxies showing strong integrated DLAs with N-HI > 10(21) cm(-2) only increases slightly from approximate to 60% at z approximate to 6 up to approximate to 65 - 90% at z > 8. Similarly, the prevalence and prominence of Ly alpha emission is found to increase with decreasing redshift, in qualitative agreement with previous observational results. Strong Ly alpha emitters (LAEs) are predominantly found to be associated with low-metallicity and UV faint galaxies. By contrast, strong DLAs are observed in galaxies with a variety of intrinsic physical properties, but predominantly at high redshifts and low metallicities. Conclusions. Our results indicate that strong DLAs likely reflect a particular early assembly phase of reionization-era galaxies, at which point they are largely dominated by pristine H I gas accretion. At z = 8 - 10, this gas gradually cools and forms into stars that ionize their local surroundings, forming large ionized bubbles and producing strong observed Ly alpha emission at z < 8.